Antivirus Software - Network

This is a discussion on Antivirus Software - Network ; We are an adult education institution which is part of the LEA (Local
Education Authority) and run two servers with 50 client computers, the
servers are running Windows NT4 and the client machines are running
Windows 98 &amp; Windows XP.
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Antivirus Software

We are an adult education institution which is part of the LEA (Local
Education Authority) and run two servers with 50 client computers, the
servers are running Windows NT4 and the client machines are running
Windows 98 & Windows XP.

Can anyone suggest or give us any information on prices and source
about a good Anti-Viral software that will run on the system we have
(ideally we would like a server based antivirus software that is
installed on the server and automatically update the client machines).